Levulinic acid, or 4-oxopentanoic acid, is the simplest member of the comparatively rare class of organic compounds known as gamma-keto acids. Having both a ketonic carbonyl group and an acidic carboxyl group, it reacts as a ketone and as a fatty acid. The chemical structure of levulinic acid may be represented as: EQU CH.sub.3 COCH.sub.2 CH.sub.2 COOH
Levulinic acid is a starting product for the preparation of organic chemicals, dyestuffs, polymers, pharmaceutically active compounds, and flavor substances. Levulinic acid is also an inhibitor of chlorophyll synthesis. Where levulinic acid is utilized in edible compositions rigorous purity, color and stability requirements must be met.
Esters of levulinic acid are known to be useful as plasticizers and solvents, and have been suggested as fuel additives. Levulinic acid is useful as a solvent, food flavoring agent and as a starting material in the preparation of a variety of industrial and pharmaceutical compounds such as diphenolic acid (useful as a component of protective and decorative finishes), calcium levulinate (a particularly suitable form of calcium for intravenous injection used for calcium replenishment and to treat hypocalcemic states, see Cox et al., U.S. Pat. No. 2,033,909).
Levulinic acid is also useful in preparing a glass-like synthetic resin and as a constituent of hydraulic brake fluids and in the manufacture of nylon and rubber. The use of the sodium salt of levulinic acid as a replacement for ethylene glycols as an antifreeze has also been proposed.